CY28405OC-2 SPECTRALINEAR [SpectraLinear Inc], CY28405OC-2 Datasheet - Page 7

• Manufacturer Part Number: CY28405OC-2
• Description: Clock Synthesizer with Differential SRC and CPU Outputs
• Manufacturer: SPECTRALINEAR [SpectraLinear Inc]

Rev 1.0, November 22, 2006
Byte 6: Control Register (continued)
Byte 7: Control Register
Crystal Recommendations
The CY28405-2 requires a Parallel Resonance Crystal.
Substituting a series resonance crystal will cause the
CY28405-2 to operate at the wrong frequency and violate the
ppm specification. For most applications there is a 300-ppm
frequency shift between series and parallel crystals due to
incorrect loading.
Table 6. Crystal Recommendations
Crystal Loading
Crystal loading plays a critical role in achieving low ppm perfor-
mance. To realize low ppm performance, the total capacitance
the crystal will see must be considered to calculate the appro-
priate capacitive loading (CL).
The following diagram shows a typical crystal configuration
using the two trim capacitors. An important clarification for the
following discussion is that the trim capacitors are in series
with the crystal not parallel. It’s a common misconception that
load capacitors are in parallel with the crystal and should be
approximately equal to the load capacitance of the crystal.
This is not true.
14.31818 MHz
Frequency
Bit
Bit
2
1
0
7
6
5
4
3
2
1
0
(Fund)
@Pup
@Pup
0
1
1
0
1
0
0
1
0
0
0
Cut
AT
PCIF
PCI
3V66
SRCT,SRCC
CPUT_ITP,CPUC_ITP
REF_1
REF_0
Revision ID Bit 3
Revision ID Bit 2
Revision ID Bit 1
Revision ID Bit 0
Vendor ID Bit 3
Vendor ID Bit 2
Vendor ID Bit 1
Vendor ID Bit 0
Loading Load Cap
Parallel
Name
Name
20 pF
0.1 mW
Revision ID Bit 3
Revision ID Bit 2
Revision ID Bit 1
Revision ID Bit 0
Vendor ID Bit 3
Vendor ID Bit 2
Vendor ID Bit 1
Vendor ID Bit 0
(max.)
Spread Spectrum Enable
0 = Spread Off, 1 = Spread On
REF_1 Output Enable
0 = Disabled, 1 = Enabled
REF_0 Output Enable
0 = Disabled, 1 = Enabled
Drive
Shunt Cap
(max.)
5 pF
Figure 1. Crystal Capacitive Clarification
Motional
0.016 pF
(max.)
Description
Description
Tolerance
50 ppm
(max.)
Stability
50 ppm
CY28405-2
(max.)
Page 7 of 16
(max.)
Aging
5 ppm